The present invention relates to a new and improved construction of apparatus for locking essentially free of play a component or part which can be oriented in a defined position, especially a drive shaft rotatably mounted in a housing. The drive shaft is provided, for instance, for the elevation or azimuth movement of a sighting or aiming device or the like of an observation periscope and can be positioned in predetermined rotational positions.
For the purpose of arresting the elevational movement of a reflector or mirror in a periscope there is known to the art from German Pat. No. 2,030,735 an apparatus wherein a component which performs the elevational movement can be rotated by means of a shaft which can be locked in a desired terminal or end position in order to determine the line of sight. The locking action is essentially accomplished by two locking elements arranged in spaced relationship from one another and rigidly connected for rotation with the shaft as well as by two further locking elements attached at a component or part arranged in spaced relationship from the shaft. These two further locking elements can be moved to-and-fro by a magnet and in the locking position are form-lockingly and force-lockingly connected with both of the first locking elements. This apparatus is afflicted with the drawback that in the presence of even the slightest amount of wear the interengaging locking elements no longer ensure for the accuracy required for such type of optical equipment.
Other exemplary constructions of prior art equipment have been disclosed, for instance, in French Pat. Nos. 2,096,311 and 2,420,405 and German Patent Publication No. 1,948,046 and German Pat. Nos. 1,578,279 and 1,268,934.